Universal connector for cable conductors

ABSTRACT

A ELECTRICAL CONNECTOR IS DISCLOSED HAVING A CAPABILITY FOR BOTH BUTT-SPLICING AND BRIDGE-SPLICING A PLURALITY OF INSULATED WIRES WITH SOLDERLESS CONNECTIONS. THE CONNECTOR INCLUDES A METALLIC CONTACT CONTAINING A PLURALITY OF TAPERED SLOTS, THE SIDEWALLS OF WHICH ARE FORMED TO PIERCE THE INSULATION ON THE WIRE. THE PORTION OF THE CONTACT AT THE ENTRANCE TO THE SLOTS IS FORMED INTO A SHOULDER TRANSVERSE TO THE AXIS OF THE SLOTS. AS A RESULT, WHEN INSULATED WIRES ARE FORCED INTO THE SLOTS OF THE CONTACT, THE INSULATION IS PIERCED, THE SHOULDER HOLDS THE INSULATION TO PREVENT IT FROM BEING DRAWN INTO THE SLOT, AND POSITIVE ELECTRICAL CONTACT IS ESTABLISHED BETWEEN THE CONDUCTORS OF THE WIRES AND THE METALLIC CONTACT. A RETAINER IS ALSO PROVIDED TO HOLD THE WIRES IN PLACE PRIOR TO BEING FORCED INTO THE SLOTS AND TO PROVIDE MECHANICAL SUPPORT FOR THE WIRES AFTER THE CONNECTION IS MADE.

Feb. 27, 1973 J. P. PASTERNAK UNIVERSAL CONNECTOR FOR CABLE CONDUCTORSFiled Jan. 4. 1971 3 Sheets-Sheet 1 //Vl/EN TOR By J. P. PASTER/VAK figW A TTOR/VEV Feb. 27, 1973 J. P. PASTERNAK UNIVERSAL CONNECTOR FOR CABLECUNDUC'IORS 3 Sheets-Sheet I filed Jan. 4, 1971 FIG. 4

FIG. 5

Feb. 27, 1973 J. PASTERNAK lJNlVljHli/xb CONNECTOR FOR CABLE CONDUCTORS3 Sheets-Sheet 5 Filed Jan. 1, i971 United States Patent ()fiice3,718,888 Patented Feb. 27, 1973 3,718,888 UNIVERSAL CONNECTOR FOR CABLECONDUCTORS John Paul Pasternak, Plainlield, N.J., assignor to BellTelephone Laboratories, Incorporated, Berkeley Heights,

' Filed Jan. 4, 1971, Ser. No. 103,687

Im. or. non 11/20 US. Cl. 339-98 Claims ABSTRACT OF THE DISCLOSURE Anelectrical connector is disclosed having a capability for bothbutt-splicing and bridge-splicing a plurality of insulated wires withsolderless connections. The connector includes a metallic contactcontaining a plurality of tap ered slots, the sidewalls of which areformed to pierce the insulation on the wire. The portion of the contactat the entrance to the slots is formed into a shoulder transverse to theaxis of the slots. As a result, when insulated wires are forced into theslots of the contact, the insulation is pierced, the shoulder holds theinsulation to prevent it from being drawn into the slot, and positiveelectrical contact is established between the conductors of the wiresand the metallic contact. A retainer is also provided to hold the wiresin place prior to being forced into the slots and to provide mechanicalsupport for the wires after the connection is made.

BACKGROUND OF THE INVENTION This invention relates to solderlesselectrical connectors, and particularly to such connectors as areadapted for permanently splicing together insulated wires. A typicalapplication for such connectors is in the splicing of plastic-coveredcopper or aluminium wire at telephone cable junctions.

A solderless connector of this type generally includes three main parts:a base, a contact, and a cover. The base is an insulating piece havingtunnels or channels into which the wires to be interconnected areinserted. The cover is also an insulator and is arranged tosubstantially enclose the base. The contact is a conductive metallicpiece having a plurality of wire receiving slots cut into it. Thepressing action of mating the base and the cover together is arranged toforce the wires into the slots in the contact. The side walls of theslots have a configuration for piercing the insulation on the wires,making contact with the conductors of the wires, and therebyinterconnecting the conductors of the various wires through the contactpiece.

In the past, these connectors have been used with insulated wire havinga copper conductor. Good mechanical connections were obtained that wereable to retain a low resistance despite mechanical stresses, repeatedtemperature changes or pressure changes, exposure to moisture, and thepassage of electrical current. The necessity for stripping insulationfrom the wires to be terminated was precluded by the ability of theconnector to penetrate the insulation and make positive metal-to-metalcontact. Furthermore, copper oxidizes rather slowly. As a result, it wasnot necessary to seal the solderless connector to prevent degradation ofthe termination due to oxide formation. Since these connectors were alsoadaptable to mechanization, a high installation rate was obtained with aresulting low cost.

Copper has now become in short supply and accordingly become relativelyexpensive. For this reason in particular, consideration has recentlybeen given to using aluminum to replace the copper conductor ininsulated wire. Aluminum is abundant, relatively inexpensive, and

lightweight. It also has electrical properties close to those of copper.The mass conductivity of aluminum is more than twice that of copper.Aluminums volume conductivity, however, is only approximately two-thirdsthat of copper. As a result, a copper conductor will weigh twice as muchas an aluminum conductor of the same physical size, yet the conductanceof the aluminum conductor will be only approximately 60% that of thecopper conductor. Therefore, while an aluminum conductor having the samecurrent carrying capacity as a copper conductor will only weigh half asmuch, it will also be slightly larger physically.

For example, to use an EC grade aluminum conductor to replace a copperconductor, while maintaining the same conductance, the aluminumconductor must be 2 AWG sizes larger than the copper conductor itreplaces. Of course, any connector designed for use with aluminumconductors should retain all the advantages of connectors designed forcopper conductors, and, in fact, should also be suitable to connect toaluminum or copper conductors with equal facility. At the same time,such a connector must be capable of coping with the special problemspresented by aluminum conductors.

An oxide film forms on analuminum surface Within seconds after baremetal is exposed. The film will normally attain a thickness of from 60to angstroms, but may reach as high as several thousand angstroms underconditions of extremely high humidity and temperature. The oxidation ofaluminum is self-limiting because the films density, amorphous nature,and low ionic conductance prevent progressive oxidation. Electricalcontact with an aluminum conductor is relatively poor through the oxidesince the dense, inert aluminum oxide surface film is non-conducting.Before a good electrical joint can be made, the oxide film must beremoved or penetrated so that bare metal surfaces will be in intimatecontact with one another.

The aluminum oxide surface film is brittle and so will not follow theplastic deformation of the underlying aluminum conductor. However, thefilm will fracture at points of high stress and deformation, allowingbare metal surfaces to be exposed. This means that where 10- calizedstress is applied to an aluminum wire, the oxide film may be fracturedand effective electrical contact established. Since aluminum isparticularly subject to creep or cold flow, this contact stress willeventually be accommodated by movement away from the stressed area. Therate of creep increases with temperature and is noticeably higher foraluminum than it is for copper. Thus, the contact pressure of aconnector decreases more rapidly for an aluminum conductor than it doesfor a copper conductor. As a result, the critical level at which contactdegradation occurs is reached much sooner with aluminum than it is withcopper.

Beyond the problems created by the presence of the skin of aluminumoxide, aluminum conductors do not have the mechanical strength thatcopper conductors have. Since aluminum has a much lower yield strengththan copper, only approximately 40%, and since aluminum is relativelynotch sensitive, the aluminum conductor wire must be mechanicallysupported to prevent fracture of the aluminum conductor at the jointresulting from any external stressing of the connected wires. This is aparticular problem when a connector capable of piercing the plastic Wireinsulation is contemplated. In order to pierce the insulation andpenetrate the underlying oxide coating, the aluminum conductor must bedeformed and extruded. This flattens or notches the conductor at thetermination joint, giving it a reduced cross-sectional width thatgreatly weakens the aluminum and makes it particularly susceptible tomechanical failure.

Since aluminum conductors extrude so readily, particular care must betaken to prevent any undesirable type of extrusion due to the presenceof surface irregularities or burrs at the entrances to the slots in thecontact piece. Also since the aluminum has a low yield strength, anyover-extrusion of the conductor at the entrance to the contact slotreduces the intimate metal-to-metal and electrically conductive contactbetween the conductor and the sidewalls of the slot in the matedconnector. This loss of intimate contact creates an unworkable andunstable connection because the resulting low pressure between the slotsidewalls and the conductor permits air to react with the surface of thebared aluminum conductor and reoxidize it at the joint.

Another problem arises where tough plastic insulation is used overaluminum conductors, such as polypropylene. The toughness of thismaterial may require such a high contact pressure to pierce theinsulation that the yield strength of the aluminum conductor isexceeded. As a result, piercing the insulation may extrude the aluminumconductor without establishing electrical contact.

This problem is aggravated where it is desired to use a single sizeconnector on a wide range of wire gauges. The width of the slot must beless than the diameter of the smallest conductor contemplated, For largeconductor wires an excessive pressure may thereby result. If the slotwidth is increased to avoid this problem, the piercing pressure willthen be too low for small diameter wires. This will result in theinsulation not being completely pierced. Because of this, a layer ofinsulation will remain between the conductor and the contact of theconnector and electrical contact will not be established. Theperformance of a termination is determined by the contact resistance ofthe joint interface. Since aluminum oxide is essentially nonconductive,the presence of an oxide coating at the interface decreases theeffective contact area available tocarry current. This increased contactresistance could impair transmission. Since aluminum has a greatertendency to oxidize than copper, a practical termination must overcomethis problem while accommodating the lower mechanical properties thataluminum has. The special problems of terminating aluminum con ductorwire have been a deterrent to the widespread use of aluminum.

Not only is it necessary to establish an initially low resistancetermination, but also to preserve the stability of even the best joint.Accordingly, the termination or joint interface must be sealed toprevent air from entering the interface and surrounding bored conductorto oxidize the aluminum. Otherwise, as stress is relieved with time andthe contact pressure decreases oxidation can occur as relative movementdue to temperature changes and the difference in thermal expansioncauses areas of aluminum to be exposed.

Another important factor affecting the electrical stability of atermination is the effect of daily or seasonal temperature changes.Since different conductor metals expand and contract at varying rates,relative movement between contacting members of different metals occurswith temperature changes. A joint that initially has a low resistancemay develop a much higher resistance when heated or cooled, yet maystill return to a low resistance when the initial temperature returns.For example, when an aerial cable is terminated on a telephone pole, thetemperature inside a termination closure may reach 140 F. A suddenthunderstorm may cause wind-driven rain to plunge the temperature to 70F. in minutes. This rapid change in temperature causes a conductor tomove relative to any other metal which it contacts.

This relative movement resulting from temperature fluctuations may causean initially low resistance termination to become a high resistancetermination. This occurs where the movement of the aluminum conductorbrings a port on of h oxide sea g in; s n act wi h e connector. Asubsequent change in temperature may again cause contact to beestablished with a portion of the aluminum conductor. The intermittentnature of such an unstable termination would generate as muchtransmission difiiculty as a continuous high resistance termination, yetin some ways he even more of a problem. A high resistance terminationcan be readily found by testing, but an unstable termination isfrequently within test limits whenever a test is performed, yet willgenerate customer complaints due to the instability of the termination.Further, if the termination is not sealed, an unstable termination willprogressively deteriorate with time since the relative movement willexpose the initially clean alu minum to the air which causes it tooxidize.

Differences in thermal expansion rates of other materials used withaluminum can aggravate the cold flow problem. For example, if analuminum to copper joint is heated, the aluminum expands at a rate 40%to 45% greater than that of copper. If the mechanical stresses increaseuntil the elastic limit of the aluminum is exceeded, plastic deformationwill occur. When the joint is subse quently cooled, the contact area ofthe aluminum and the contact pressure are reduced. Again, this permitsthe formation and penetration of an oxide film into the contact area.

One of the most common methods for terminating aluminum conductor wire,up until now, has been by crimping. Here the two conductor wires to beterminated are stripped and the stripped ends inserted into a hollowsleeve. The sleeve is then crimped by a tool with sufficient force tocause plastic flow at the interior of the termination. To avoid thenecessity for stripping the wire ends prior to termination, a secondmethod was used where the sleeve was punched after being inserted overthe insulated wire ends. The punching pierced the insulation andestablished contact between the wire ends and the sleeve. This secondmethod, however, is generally limited to wire with paper insulation. Fewembodiments of the punching operation are effective to pierce plasticinsulation and establish contact with the underlying conductor.

Since telephone cables are designed for a minimum serviceability lifespan of forty years, it is apparent that a stable joint is a necessity.Also, since wire joints and terminations must be connected in series, ahigh reliability, low resistance joint is essential to meet transmissioncriteria. A connector with initially low resistance is not sufficientunless the low resistance can be maintained for a long period of time inthe presence of temperature changes and the application of mechanicalstresses. The desirability for providing a solderless connector capableof connecting aluminum wires is clear. The advisability for making sucha connector compact, inexpensive and simple to use is also clear.Although such connectors have been designed for use with copperconductors, up until now attempts to apply such devices for aluminumconductors have been precluded by the special requirements dictated bythe peculiar properties of aluminum.

Solderless connectors have been known and used for some time. An exampleof a connector adapted for buttsplicing, or connecting together severalwire ends, is US. Pat. No. 3,012,219, issued Dec. 5, 1961, to E. J.Levin et al. An example of a connector adapted for bridgesplicing, orconnecting wire ends to a continuous wrie, in US. Pat. No. 3,118,715,issued Jan. 21, 1964, to R. A. Potruch. Although devices such as theseare effective when used to splice Wires having copper conductors, theforegoing shows that ditferent technical considerations are involved insplicing aluminum conductor wire.

It is therefore an object of my invention to prevent the increasedresistance between solderless connectors and aluminum conductors ofinsulated wires by piercing the oxide layer of the conductor andpreventing the subsequent formation of an oxide coating between the sidewalls of the contact and the conductor,

It is a further object of my invention to control extrusion of thealuminum conductor at the entrance to the slots in the metallic contactof these connectors, thereby preventing connections in which an air gapexists between the side walls of the contact and the conductors of thewires, thereby maximizing the elfective contact area between theconductor and the contact.

Still another object of my invention is to prevent the formation of aninsulation film between the side walls of the contact and the conductorsby restraining the insulation from being drawn down into the slots inthe contact.

Yet another object of my invention is to permit a single connector to beused interchangeably for either buttsplicing or bridge-splicing.

It is also an object of my invention to provide mechanical support tothe wires leading from the connector and prevent mechanical failure dueto tensional or torsional stresses applied to the wires.

It is still a further object of my invention to permit a singleconnector to be used interchangeably for a variety of Wire sizes.

SUMMARY OF THE INVENTION In an illustrative embodiment of my invention,the connector includes a base, a cover, and a contact containing aplurality of inwardly tapering slots, the entrances of which include ashouldered portion transverse to the aixs of the slots. A plurality ofwires to be interconnected is inserted into tunnels in the base wherethey are held in position. To prevent mechanical failure of thetermination joint due to the brittleness of the aluminum conductors andthe resultant weakness at the joint, the wires are supported by the baseagainst torsional or tensional stresses which may be applied to thewires. The interconnection of the plurality of wires is accomplished byforcing the cover over the conductive metallic contact where it mateswith the base. This causes the wires to be forced into the slots in thecontact, pierces the insulation, and establishes an electricalconnection between the contact of the connector and the conductors ofthe wires. The body of the connector is adapted to butt-splice a plurality of wire ends and is readily converted to bridgesplicing one ormore wire ends to a continuous wire.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of anassembled connector shown butt-splicing three wire endstogether.

FIG. 2 is a perspective view of an assembled connector showing two wireends bridge-spliced to a through going wire.

FIG. 3 is an exploded perspective view showing the elements of theconnector arranged for butt-splicing.

FIG. 4 is a cross-section of the connector shown prior to theinterconnection of the wires.

FIG. 5 is a cross-section of the connector shown with the base and covermated and the wires interconnected.

FIG. 6 is a perspective view of a practical cross-section of theconnector base showing a wire end in place for a splice.

FIG. 7 is a partially exploded perspective view of the connector baseshowing the base adapted for use as a bridge-splice connector.

FIG. 8 is a partial cross-section of the connector shown in FIG. 2.

FIG. 9 is a perspective of the contact of the connector showing a wirein its connected position.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT A solderless connectorembodying my invention is shown in FIGS. 1 through 9. FIG. 1 shows theconnector used to buttsplice three wire ends 1, 2 and 3 together. Thesame connector is shown in FIG. 2 adapted to be used for bridge-splicingtwo wire ends 1 and 2 to a through wire 4. The basic parts of theconnector, shown clearly in an exploded perspective view in. FIG. 3, area base 10, a cover 20, and a contact 30.

Base 10 includes three wire tunnels 12, 13 and 14 into which wire ends1, 2 and 3 are respectively inserted. The entrances to the tunnels arebeveled to prevent the wire ends from catching on the edge of theentrances, or hanging up, which would prevent the wire end from beinginserted all the way into the tunnels. The tunnels are blind, or closedat the far end, and it is desirable that the wire ends bottom againstthe end of the tunnels. Once inserted, the wires must be retained in thetunnels of the base to prevent the wires from backing out of the tunnelsas a result of subsequent handling.

The means for retaining the inserted wires is clearly illustrated inFIG. 6. After wire end 1 is fully inserted into tunnel 12, the free endof the wire is drawn down against retainer tab 41 and then looped undersnubber 46. As a result of the offset in the axis of wire 1, and becauseof the resiliency of retainer tab 41, a restraining force is exertedagainst wire 1. The effect of this restraining force is to grip wire end-1 between retaining tab 41 and snubber 46 and prevent wire end 1 frombacking out of tunnel 12. This insures that once inserted into one oftunnels 12, 13 or 14, a wire end will stay bottomed against the end ofthe tunnel.

The connector is shown in cross-section in FIG. 4 as it would be shippedfrom the manufacturer, except wire ends 1, 2 and 3 which are shown inplace in tunnels 12, 13 and 14 are naturally, not shipped with theconnector assembly. Pins 8 and 9 of cover 20 are inserted through holes31 and 32 respectively of contact 30. This is shown more clearly in FIG.3. The pins are then headed over to secure contact 30 to the inside ofcover 20. (Dover 20 is equipped with lips 21 and 22 on either side whichare designed to snap into position in matching grooves 18 and 19,respectively, in base 10, thereby latching the base and cover together.As soon as wire ends 1, 2 and 3 are inserted respectively in tunnels 12,13 and 14, the wire ends are ready to be interconnected.

To interconnect the wire ends 1, 2 and 3, cover 20 and base 10 arepressed together. This forces lips 21 and 22 of cover 20 out of grooves18 and 19 in base 10 and permits the base and cover to mate. In themated position, lips 21 and 22 of cover 26 lock into position in grooves24 and 25 respectively of base 10. At the same time, the mating of thebase and the cover forces the inserted wires into slots 33, 34 and 35 ofcontact 30. As FIG. 2 shows clearly, contact 30 is U-shaped and each legof the U is slotted. A slot 33 appears in both legs, for example. Theprimary function of the double slots is the increased reliabilityresulting from the redundancy.

The details of contact 30 are shown enlarged in FIG. 9. Slot 33 incontact 30, which is representative of slots 34 and 35 as well, has aninwardly tapering shape. The sides of the slot in the far leg of theU-shaped contact 30 are defined by posts 61 and 62. The function of thecontinuously tapered slot is to prevent the conductor of wire 1 frombeing so extruded by any imperfection or burr at the entrance to slot 33that positive contact between the conductor and the sidewalls of theslot could not be made when the wire is fully in place in the slot. Thispermits relatively inexpensive manufacturing methods to be used tofabricate the contact since nominal variations in the degree of taper ofthe slot sidewalls or moderate burrs and irregularities around the slotentrance area will have little effect on the integrity of the resultingconnection.

Posts 61 and 62 include a chamfered entrance 63 which insures that theentering wire is properly positioned in the center of slot 33. At thejuncture of chamfered entrance 63 and slot 33, posts 61 and 62 areformed into shoulders 64 and 65, respectively. As explained previously,a particular problem exists where tough plastic insulation is used overan aluminum conductor. The function of shoulders 64 and 65 is to presenta large area to grip the insulation as the wire is forced into slot 33.As a result, the insulation is stripped away from the conductor withoutoverly extruding the conductor. This is necessary to prevent a thin skinof insulation from being drawn down into the slot with the conductor,preventing intimate contact between the slot sidewalls and theconductor. The action of the shoulders causes the insulation to part atthe connector leg. The parted insulation then elastically snaps backsufliciently to leave the area of slot 33 free of insulation.

Another feature of the structure of contact is perhaps best shown inFIG. 3. Between the adjacent wire slots 33, 34 and are spacer slots 55and 56. For example, between post 62 (which together with post 61defines wire slot 33) and post 66 (which together with post 67 defineswire slot 34) is a spacer slot 55. Spacer slot 55 permits post 62 to bedeflected from its initial position by a wire being forced into wireslot 33, and for post 66 to be deflected from its initial position by awire being forced into wire slot 34, or for both posts to be sodeflected. If spacer slot 55 were not present, as is true in prior artconnectors, then forcing a wire into both slots 33 and 34 would notdeflect the portion of the contact between them from its initialposition because the forces on each side would be equal. As a result, asthe conductor creeps with time, the sidewall pressure could not bemaintained because the portion of the contact between the adjacent slotswould have no stored energy due to elastic deflection. By contrast,posts 62 and 66 retain full resiliency because the presence of wires inadjacent slots does not prevent their full deflection. This insures thatas the stress relaxes with time, due to cold flow or creep of thealuminum conductor, the maximum retained stress of the deflected postswill maintain sutficient pressure against the conductor to insure a lowresistance joint.

Since it is so desirable to have the connector universally applicable,it is designed to readily convert from a butt-splicing connector to abridge-splicing connector. This feature is readily seen in FIG. 7 whereremovable plug 11 is shown broken away from base 10. Tunnel 14 in base10 is now no longer a blind tunnel but has its side and other end open.This permits base 10 to be readily installed over a through wire, even awire already wired into service. The through wire would be held byretaining tabs 42 and 43 in concert with snubbers 47 and 48 atrespective ends of tunnel 14 in a manner similar to that describedpreviously relative to tunnel 12. It is also apparent in FIG. 7 thatsimilar retaining means are not provided for tunnel 13. The retainingforce exerted on a wire inserted in tunnel 13 results from therestriction caused by torsional stops 49 and 50, whose major functionwill be explained in more detail later. It should be clear that theretaining force exerted on a wire in tunnel 13 is minimal for anythingother than a large gauge wire. However, this is of little consequencesince all other wires are firmly retained, leaving the craftsman only asingle wire to juggle.

Since aluminum conductors are so weak mechanically at the terminationjoint due to extrusion, it is necessary to provide support frommechanical stresses, both ten sional stress and torsional stress.Looking back at FIG. 3 it can be seen that cover 20 includes on itsunderside a plurality of troughs or grooves 26, 27, 28 and 29 andrelated blocks 37, 38, 39 and 40. The purpose of these elements can bemore clearly understood by referring to FIG. 8 which shows alongitudinal cross-section of a bridge-splice. The mating of the cover20 with base 10 during the connection operation causes both ends ofthrough wire 4 to be offset substantially from the axis of tunnel 14. Atthe same time, wire 4 is firmly gripped between block 39 and retainingtab 42 at its right end and between block and retaining tab 43 at itsleft end.

'8 Any tensional stress applied to the wire ends will be absorbed by theblocks 39 and 40 which prevent the stress from being transmitted to thejoint interface with connector 30 where the conductor has beenmechanically weakened by extrusion. Blocks 37 and 38 accomplish asimilar function.

The sidewalls of troughs 26, 27, 28 and 29 work in conjunction withtorsional stops 49, 50 and 51 to support the wires and prevent anytorsional stress applied to the wires from being transmitted into thearea of the termination interface. The combination of the troughs incover 20 and the torsional stops on base 10 confine the wires so thatany twisting applied to the wires is absorbed and not transmitted intothe interface.

Since aluminum conductors oxidize so readily and since a completelyair-tight, stable connection is essentially impossible with a purelymechanical connection, it is recommended that the connector include asealant to encapsulate the termination joint after the connectionoperation is completed. Using this connector, this is most effectivelydone by including a globule of sealant, such as polyethylene-polybutene,inside the cover assembly. Preferably, the sealant would be placed atthe base of the U- shaped contact 30.

As FIG. 8 clearly shows, the mating surface 6 of base 10 is concave orangled. This LS done to insure that as the base 10 and cover 20 aremated during the connection operation, the sealant will be preventedfrom escaping from the interior of the connector until the terminationis fully sealed. Rather, the sealant is forced down into openings 52 and53 in base 10 insuring that the termination interface is fullyencapsulated. If sealant subsequently is squeezed out of the connectorbecause of any excess, no harm is done because it has already beeninsured that the termination interface is fully sealed. It should alsobe pointed out that the retaining tabs 41, 42 and 43 are also useful tohold the sealant within the body of the connector. This is particularlyimportant Where all wire tunnels do not contain a wire so that withoutthe presence of the retaining tab, a clear channel out of the connectorbody would be provided by the trough in cover 20 associated with theunused tunnel.

As I disclosed in in my previous Pat. No. 3,511,921, dated May 12, 1970,contact 30 could be advantageously plated with indium. Indium is anone-oxidizing, solid but readily flowable, conductive material thatpenetrates the microscopic cracks in the aluminum oxide film. Thisaffords a good electrical contact with the pure aluminum of the aluminumconductor while reducing oxidants at the interface.

Although I would envision base 10 and cover 20 being injection moldedfrom a plastic material such as polycarbonate, other materials wouldalso prove effective. Since base 10 would advantageously be molded, theremovable plug 11 could be molded as part of base 10 but with readilyseparable perforations. This would permit only a single piece to beused, while at the same time permitting plug 11 to be readily and simplyremoved when necessary. This would avoid the necessity of fabricatingplug 11 as a separate piece and then assembling the plug with base 10.It should also be apparent that if the particular applicationcontemplated required it, a similar plug could also be included on theother side of base 10, permitting tunnel 12 to also be used to accept athrough wire.

Although the embodiment shownhas a capacity for three wire ends in abutt-splice or two wire ends and a through wire in a bridge-splice, itshould be apparent that any number of tunnels could be provided in base10 and a corresponding number of slots provided in contact 30. It isfelt, however, that the three-tunnel version would have the mostuniversal application.

The resilient nature of retainer tabs 41, 42 and 43permit the connectorto be used to effectively hold a wide range of wire gauges. Thisflexibility and universality is extended to contact 30 where the taperedslots 33, 34 and 35 are also efiective to connect a wide range of wiresizes. It should be pointed out that all the wires connected by a singleconnector need not be the same size; large gauge and fine gauge wirescan be mixed and still be readily interconnected.

Contact 30 is shown as being generally U-shaped, although this is notessential to my invention. Contact 30 could function eflecti'vely withonly a single slotted leg. However, since it is desired to establishconnections that are stable and reliable for long periods of time, theredundancy of providing a double leg would seem to be preferred.

By way of illustration, in one embodiment of my invention, slots 33, 34and 35 in contact 30 are approximately one-eighth inch deep measuredfrom the shouldered portion of the contact and approximately .012 inchwide with a one degree taper. The width of the shoulder is approximately60% of the .050 inch width of the leg of contact 30. Using thesedimensions, wire gauges in the nominal range of 17 to 26 gauge areeasily and effectively used, either all the wires being the same gaugeor any mixture of sizes within the range indicated. Of course, if itwere desired to use a different range of wire gauges, the abovedimensions could be readily altered by one having ordinary skill in theart to accommodate the revised range.

Despite the continual reference to plastic insulated wire in thespecification, it should be clear that this connector is equallyelfective with pulp insulated wire, paper insulated wire, or wireinsulated with any other common type of insulation. At the same time, itshould be clear that the connector is not restricted in its applicationto aluminum conductor wire. Wire with copper conductor, or any othermetallic conductor, could be as effectively connected as could thealuminum conductor wire. In fact, a mixture of wires having dilferentconductor materials could be interconnected with equal facility.

Finally, although reference has been made throughout this specificationto interconnecting a plurality of wires by connecting each to thecontact of the connector, it should be apparent to those knowledgeablein the art that applications arise where it might be desirable topermanently connect a wire to the contact of the connector. For example,a wire could be soldered to the contact by including a terminal on thecontact for such a purpose. Thereafter, additional wires could besolderlessly connected to the permanently connected wire as theparticular application dictated. This is within the contemplation of theinvention I have described and serves to further illustrate theuniversality of my connector.

What is claimed is:

1. A solderless connector for connecting a plurality of wirescomprising:

a base including means for accommodating the wires to be connected;

a conductive metallic contact including a pair of cantilevered posts foreach Wire to be connected, each post including a sidewall adjacent theother post of the pair and tapering continuously towards the other postat the fixed end, and each post also undergoing an abrupt change inthickness in the direction of the axis of the wire, the abrupt changebeing located adjacent the free end of the post; and

cover means for mating with the base to substantially enclose thecontact, the mating of the cover with the base being simultaneouslyeffective to force the wires into the tapered spaces between the pairsof posts;

whereby the insulation on insulated wires is restrained by the abruptchange in thickness when the base and cover are mated.

2. A solderless connector for connecting a plurality of wirescomprising:

, a base including means for accommodating the wires to be connected;wherein the means for accommodating the wires comprises:

a plurality of close-ended tunnels; and wherein the base also includesaplug separable from the base, the separation of the plug from the basebeing effective to open the side and end of one of the tunnels, therebyenabling the open tunnel of the base to be placed over the continuouswire to permit connection thereto; the connector further comprising:

a conductive metallic contact including a pair of cantilevered posts foreach wire to be connected, the adjacent sidewalls of each pair taperingcontinuously together towards the fixed end of the posts; and

a cover adapted to mate with the base thereby substantially enclosingthe contact, the mating of the cover with the base being simultaneouslyeifective to force the wires into the tapered spaces between the pairsof posts so that electrical contact is established between theconductors of the wires and the posts of the contact.

3. A solderless connector for connecting a plurality of wirescomprising:

a base including means for accommodating the wires to be connected;

a conductive metallic contact including a pair of cantilevered posts foreach wire to be connected, the adjacent sidewalls of each pair taperingcontinuously together towards the fixed end of the posts; and

a cover adapted to mate with the base thereby substantially enclosingthe contact, the mating of the cover with the base being simultaneouslyefiective to force the wires into the tapered spaces between the pairsof posts so that electrical contact is established between theconductors of the wires and the posts of the contact; wherein the coverand the base are shaped to latch to each other in two positions;

in the first position, the cover and the base latch together in aposition leaving the contact clear of the accommodated wires, and

in the second position, the cover and the base are mated.

4. A solderless connector for connecting a plurality of 50 wirescomprising:

a conductive metallic contact including a pair of cantilevered posts foreach wire to be connected, each post including:

a sidewall adjacent the other post of the pair and tapering continuouslytowards the other post at the fixed end, and

a shouldered portion adjacent the free end and forming an abrupt changein thickness in the direction of the axis of the wire;

a cover; and

a base adapted to mate with the cover thereby substantially enclosingthe contact, the mating of the cover with the base being simultaneouslyeffective to force the wires into the tapered spaces between the pairsof posts, the base including:

means for accommodating the wires to be connected comprising a pluralityof close-ended tunnels into which the wires to be connected areinserted, and

means for holding the inserted wires in position to prevent them frombacking out of the tunnels in the base prior to the mating of the coverand the base;

the insulation on insulated wires being restrained by the shoulderedportion when the base and cover are mated, so that the insulation isprevented from entering the tapered spaces between the posts, therebytearing the insulation from the conductors of the wires as the wires areforced into the tapered spaces and exposing the conductors of the wiresto permit contact to be established between the exposed conductors andthe tapering sidewalls of the posts.

5. A connector in accordance with claim 4 wherein the holding meanscomprises:

a fixed member spaced from the open end of an individual tunnel andotfset from the axis of the tunnel; and

a resilient member located between the open end of the tunnel and thefixed member, the resilient member being so located that when a wire isinserted into the tunnel and positioned in engagement with the fixedmember, the resilient member is deflected to bias the wire against thefixed member.

6. A solderless connector for connecting a plurality of insulated wirescomprising:

a base including means for accommodating the wires to be connected,wherein the base also includes:

a plurality of close-ended tunnels into which the wires to be connectedare inserted; and

a removable plug for opening the side and end of one of the tunnels topermit the base to be placed over a continuous wire, permittingconnection thereto;

a conductive metallic contact containing a plurality of slots, one foreach wire to be connected, the entrance to the slots including ashouldered portion transverse to the axis of the slots for restrainingthe insulation to prevent the insulation from entering the slots; and

a cover which mates with the base to substantially enclose the contact,the mating of the cover with the base being also effective to force thewires into the slots in the contact.

7. A solderless connector for interconnecting a plurality of insulatedaluminum conductor wires comprising:

a molded plastic base having a plurality of close-ended tunnels withchamfered entrances into which wire ends to be interconnected areinserted and including:

a removable plug for opening the side and end of one of the tunnels tocreate a trough into which a continuous wire is placed to beinterconnected with wire ends in others of the plurality of tunnels; and

retainer means for holding the inserted wires in position and preventingthe wires from backing out of the tunnels;

a metallic contact having a pair of cantilevered posts for each wire tobe interconnected, adjacent sidewalls of each pair being formed to taperinward towards the fixed end with the free end of each post having ashouldered portion transverse to the axis of the tapered slot createdbetween the posts of each pair;

a molded plastic cover formed to substantially enclose the metalliccontact and mate with the base, the cover being eifective when matedwith the base, to force the wires inserted in the base into the slots inthe metallic contact so that the posts are deflected from their initialposition, the insulation on the wires is pierced and restrained fromentering the slots, and electrical contact is made between the aluminumconductors of the wires and the metallic contact;

means for encapsulating the metallic contact and the interconnectedwires when the base and cover are mated; and

means for offsetting the wires from the axis of the tunnels to preventmechanical stress applied to the wires from being transmitted into theencapsulated area.

8. A solderless connector for connecting a plurality of plasticinsulated, aluminum conductor wires, the connector comprising:

a base having a plurality of close-ended tunnels into which one end ofeach wire to be connected is inserted;

a conductive metallic contact including a pair of cantilevered posts foreach wire to be connected;

a cover shaped to latch to the base in two positions,

in the first position the cover and the base latch together in aposition leaving the contact clear of any wires inserted into thetunnels in the base, and

in the second position the cover and the base are mated andsubstantially enclose the contact, the mating of the cover and the basebeing simultaneously effective to force the inserted wires into slotsbetween the posts of each pair so that the insulation on the wires ispierced thereby exposing the conductors of the wires and establishingintimate electrical contact between the conductors of the wires and thecontact; and

means effective when the base and cover are locked in mated position toprevent axial and torsional stresses applied to the wires from beingtransmitted to the juncture between the conductors of the wires and thecontact; wherein the cover also includesa chamber for containing avolume of sealant; the base also includesresilient means for securingany wires inserted into the tunnels of the base so that the wires cannotmove out of position prior to the mating of the base and the cover, and

a concavity positioned to insure that the sealant contained in the coverwill completely encapsulate the juncture between the contact and theconductors of the wires thereby producing an air-tight sea] at thejuncture; and

the posts of the contact also include a tapered sidewall on the edgeadjacent the other post of the pair thereby forming an inwardly taperingslot into which the wires are forced so that unintended extrusion of thealuminum conductors is prevented prior to the conductors reaching aseated position in the slot, and

a shoulder transverse to the axis of the slot for restraining theinsulation of the wires to prevent any insulation from entering theslots and interrupting the establishment of intimate electrical contactbetween the conductors of the wires and the contact.

9. A connector in accordance with claim 8 wherein the base alsoincludes:

a plug separable from the base, the separation of the plug from the basebeing effective to open the side and end of one of the tunnels, therebyenabling the open tunnel of the base to be placed over a continuous wireto permit connection thereto.

10. A connector for use with insulated wire and having a conductivecontact with a slot narrower than the width of the conductor of the wireto be connected, electrical contact being made with the conductivecontact as the wire is forced into the slot wherein the improvementcomprises:

means for deforming the insulation on the wire including a thin portionof the conductive contact adjacent to the entrance of the slot;

means for both restraining the insulation from further entrance into theslot and for tearing the insulation and exposing the conductor of thewire, said means including an abrupt change in thickness in theconductive contact in the direction of the wire axis; and

means for establishing electrical contact with the exposed conductorincluding a thick portion of the 3,012,219 conductive contact. 3,573,7103,576,518 References Cited UNITED STATES PATENTS 5 560 583 3,573,7134/1971 Enright et a1 339-98 3,233,206 2/1966 Fiala 339-98 3,496,5222/1970 Ellis, Jr. et al 339-99 R 2,810,115 10/1957 Abbott 339-97 P3,377,611 4/ 1968 rPawl 339-97 -P 339-403 M 3,511,921 5/1970 Pasternak339-98 14 12/1961 Levin et a1 339-98 4/1971 Wotford 339-94 M 4/1971Bazille, Jr. et a1 339-98 FOREIGN PATENTS 9/1957 Belgium 339-103 RJOSEPH H. MCGLYNN, Primary Examiner U.S. Cl. X.R.

